In many instances it is desirable to have available a structure which can be readily assembled and disassembled for temporary use and which can be easily stored when not in use. For example, in schools or other institutions such structure could be used for educational purposes as a temporary planetarium for providing instruction in astronomy. Since a permanent planetarium is generally not feasible for most such educational institutions, it is desirable to have available a structure which is relatively inexpensive, can be stored in a relatively small space, and which can be relatively easily assembled for use in a schoolroom, an auditorium, a gymnasium, or the like, on a temporary basis and then readily disassembled and re-stored.
Other exemplary applications of such structures might be as playhouses for children, as darkrooms for photography enthusiasts, or for other purposes both educational or recreational as may be conceived by those in the art.
A prior art structure which has been disclosed for use only as a portable planetarium is described in U.S. Pat. No. 3,250,024, issued on May 10, 1966, to Douthitt et al. As disclosed therein the planetarium is of the inflatable type which employs a self-supporting fabric structure that includes a hemispherical dome having its peripheral edge connected with an upright wall that serves to support the dome with respect to the ground or floor surface upon which the overall unit is placed. The unit is thereupon inflated with air so as to be generally self-supporting, the air pressure being controlled by various baffling means to maintain a substantially constant contour to the inflated planetarium. The interior of the fabric is darkened and made as light-free as possible so that the overall structure can be utilized in a fully lighted room. The structure can be set up and dismantled, as needed, and, when used with a suitable planetarium projector, is intended to provide a relatively accurate representation of a planetarium display.
The structure disclosed in the Douthitt et al. patent appears to require relatively costly fabrication of the elements involved and its complexity appears to make the fabrication and use thereof more complicated than is desirable. Accordingly, no apparent market for such apparatus has been successfully penetrated by the Douthitt et al. apparatus.
It is desirable to make available a unit which can be purchased at much lower cost than that of the Douthitt et al. structure, either by schools and the like or by individuals for home use. Such unit should be capable of substantially complete collapsibility in a manner such that it can be packed in a relatively compact manner so as to take up little space in storage. Further, the unit should be easily assembled and disassembled so that valuable educational time will not be lost in the assembly and disassembly process. Unfortunately, such relatively inexpensive and easy to use structures of this type are not available in the present day marketplace.